Comparison of different actuation modes of a biomechanical human arm model in an optimal control framework

Modelling and controlling a digital human model (DHM) is a challenging task, and the scope of ergonomic evaluation adds some additional requirements to the generated motions. In previous publications, we introduced a multibody system dynamics approach for DHM modelling with an optimal control (OC) framework for motion generation that uses different actuation modes (AM). Human bones are modeled as rigid bodies and connected via joints, as actuators joint torques (AM-T) or simplified hill type muscles are implemented. The latter can be controlled directly (AM-M) or by using muscle synergies as control parameters (AM-S). In this paper, we investigate the characteristics of human reaching motions measured in the motion lab at a "basic reaching test". We then simulate the reaching motions under similar specifications as done in the experimental setup, and compare the influence of the different actuation modes to the measured trajectories and velocity profiles.